Using dGPU AND iGPU is faster?

[CheeseAndJamSandwich]

Reading the forums, articles, manual, etc, it says to only enable the discrete GPUs if you have them.
But i've done a little bit of testing, and it seems that Aligning and Building Mesh (from Depth Maps) is actually faster with both the discrete and integrated GPUs enabled for aligning and meshing.

Align Photos:  25:33  vs.  23:42
Build Mesh:  19:41  vs.  16:00
Build Texture:  Coming soon...

Hardware:
Thinkpad P51 laptop
CPU: Intel Xeon E3-1505M v6 (Undervolted 100mv)
iGPU: Intel HD Graphics P630
dGPU: Quadro M2200
Using external display, so it's driven by the dGPU rather than the iGPU.
Metashape Standard v1.7.3 build 12473 (64 bit)


I've also previously tested a different model, repeating the test back and forth, and it saw a similar result each time.  Unfortunately i didn't keep the times.
The result I'd gotten for the Build Texture did show that it was slower for that task with the iGPU also enabled.

Is it common that this may be the case?
Or perhaps just with my combination of hardware?
That my laptop is driving the display with the dGPU, leaving the iGPU idle?
Differences with using Depth Maps?
Or changes in the engines?

Does enabling 'Use GPU while performing GPU accelerated processing' always slow it down too? 

[Alexey Pasumansky]

Hello CheeseAndJamSandwich,

Intel HD card should be ignored for texture blending operation, so it shouldn't have any noticeable effect for Build Texture task timing, whether you have Intel GPU enabled or not.

As for the other tasks, the installed GPU model is quite old, so the processing performance may be not that high and you can still get additional speed up, when both NVIDIA and Intel GPUs are enabled.

Enabling CPU flag, however, would likely affect the processing performance.

[CheeseAndJamSandwich]

Thanks for the reply.

Every test i've done, the iGPU being enabled actually did slow down the Build Texture job a fair bit.  So i've been turning it off for that part of the workflow.

So if you have a crappy, slow dGPU, enabling the iGPU can help...

I'll continue using both during my aligning and meshing.

Cheers.